In general, an ice water purifier is a device that purifies raw water such as tap water and provides a user not only with purified cold and/or hot water, but also with ice by freezing purified water (or cold water). The ice water purifier typically includes a filter that purifies raw water, a purified water tank that stores purified water, a water cooler tank that cools and stores purified water, and an ice making unit that produces ice. The ice water tank may further include a water heater tank that heats and stores purified water.
This ice water purifier has a similar configuration to a typical ice maker except that the ice water purifier includes water tanks such as a water cooler tank or a water heating unit tank. Thus, the ice water purifier may be understood as a unique type of ice maker.
Hereinafter, an ice maker will be described using an ice water purifier as an example.
In order to produce ice using an ice maker, a spraying method and an immersion method may be used among known ice-making methods. As for the spraying method such as nozzle spraying or cell spraying, water is sprayed onto a cooled ice-making water tray using a spray pump and is grown into cup-shaped or bell-shaped ice pieces. As for the immersion method, water is supplied to an ice-making water tray, and an immersion pipe of an evaporator is then cooled such that bell-shaped ice pieces with holes in their centers are produced. A spray-type ice making unit is capable of producing clear ice but is relatively expensive, whereas an immersion-type ice making unit is cheaper but is disadvantageous in that air bubbles are trapped in ice, causing the ice to have an opaque appearance. For this reason, typical ice water purifiers employ the immersion type ice making unit which is relatively economical and simple in structure, and easily produces ice.
In the immersion type ice making unit, an immersion pipe, connected to an evaporator, is immersed in water received in a water tray member, and ice is formed around the immersion pipe.
However, when raw water for ice-making received in the water tray member is low in temperature, ice may rapidly grow around the immersion pipe at the initial stage of an ice making process due to the low temperature of a refrigerant introduced into the evaporator, and this may cause air bubbles to be trapped in that area, thereby creating an opaque layer.
In particular, the opacity of ice formed around the immersion pipe is increased when the temperature of raw water for ice-making is low (e.g., lower than 5° C.) as in the case that cold water is supplied to a water tray member or raw water, remaining after the termination of an ice making process, is re-used in the next ice making process.
Since an opaque layer is formed in the ice at the initial stage of the ice making process, the transparency of the ice is lowered even if air bubbles are prevented, thereby impairing the quality of ice.
Furthermore, a related art ice maker provided with the immersion type ice making unit has a complicated bubble prevention structure which is difficult to control.